Operate and maintain a cell culture laboratory to conduct in vitro assays primarily on materials from natural sources and additionally on selected synthetic materials. Cultivate cells for stock lines and testing. E aluate and record test results and report these results to NCI. Carry out testing of meterials in accordance with protocols and procedures established by NCI. Conduct non-protocol testing related to specific questions which may arise during evaluation of new drugs. Conduct methodological research up to 10% of overall in vitro screening effort.